With the phase-out of certain environmentally damaging CFC compounds, new HCFC compounds have been offered. CFC numbers R11 (CC1.sub.3 F) and R12 (CC1.sub.2 F.sub.2) are currently targeted for replacement. HCFC types designated R123 (CHC1.sub.2 --CF.sub.3) and R141b (CC1.sub.2 F--CH.sub.3) are currently being utilized as chemical blowing agents and have been shown to exhibit severe attack on certain conventional thermoplastic polymeric compositions rendering these useless in direct contact with R123 and R141b.
Polyvinyl chloride (PVC) would have chemical resistance to R123 and 141b, however many formulated PVC compounds show some detrimental effects, and lack several properties for successful commercial applications for instance in housings and components in direct contact with blown-in foams containing HCFC compounds. Typically, conventional PVC compositions have insufficient heat deflection temperature for some of these applications, and typically have unacceptable thermoforming properties such as a limited draw-ratio of original thickness to drawn thickness. More over, formulated PVC compounds having a heat distortion additive were observed to be deficient in chemical resistance due in part to higher required impact modifier levels which interfered with HCFC resistance. Because PVC has some inherent favorable properties, it would be desirable to provide PVC based compositions and thermoformed articles derived therefrom which exhibit a combination of properties rendering these useful in applications where direct contact with HCFC chemicals may be necessary.